1. Field of the Invention
This invention relates to in-line roller skate wheels and more particularly to a prepressurized pneumatic skate wheel of integral construction having an internal bladder network.
2. Description of the Prior Art
Roller skates of various types are well known in the art. Early roller skates typically incorporated four wheels per skate. The wheels for outdoor skating were often constructed of metal and those for indoor, rink skating, of wood. In some early work pneumatic wheel construction was proposed incorporating conventional tire casings lined with a conventional inner tube. A device of this type is disclosed in U.S. Pat. No. 988,533 to Zverina.
With the advent of polyurethane wheel construction, outdoor skating gained great popularity. It was then proposed to mount a plurality of wheels in line on a skate frame so the skater could experience skating maneuvers, similar to that experienced by ice skaters skating on a single blade skate. In-line roller skating has since become a fast growing recreational activity which has developed into a major commercial market in the United States and elsewhere. In-line roller skates allow the skater to negotiate many different surfaces while enjoying the benefits of outdoor activity and cardiovascular exercise.
For recreational activity, in-line skaters often skate on boardwalks, sidewalks and streets, the surfaces of which exhibit bumpy, uneven or rough terrains. The more experienced in-line skaters often become involved in sports, such as in-line hockey, which require more precision and speed. Generally, in-line skate wheels are constructed of hubs surmounted by a tire body of solid polyurethane. Although such wheels are known to provide a relatively smooth ride over many surfaces, the solid tire body is restricted in its ability to cushion and absorb the shock associated with different loads applied due to encounters with irregular support surfaces. Since in-line wheels intended for outdoor use are subjected to numerous different side loads resulting from inclination of the skate during turns and the like, as well as sharp shock loads, the challenges encountered by designers of in-line skate wheels are far different from those encountered by designers of conventional skate wheels.
Although resilience and speed are important characteristics of these in-line skate wheels, the ability to absorb shock is critical for a comfortable ride. An in-line skate wheel that can absorb energy more efficiently while the tire is traversing rocks, gravel or other road hazards, decreases the potential for injury to the skaters legs and knees through shock, as well as creating a smooth and more comfortable ride. In-line skate wheels currently on the market offer reasonable shock absorption depending on the size and resiliency of the wheel. But, because the shock absorption properties are predetermined, the amount of protection a particular wheel provides is limited to those predetermined parameters.
Efforts to solve some of these problems led to the development of a wheel incorporating a hard polyurethane hub having a soft solid polyurethane body formed thereon to provide cushioning. A wheel of this type is disclosed in U.S. Pat. No. 5,312,844 to Gonisor. Wheels of this type have gained acceptance in the market but have some drawbacks. It has been found that solid tire construction foregoes the advantages often associated with the characteristic of pneumatic tires.
A need has remained for a wheel which will combine the benefits of cushioning long associated with a thick body of soft polyurethane with the shock absorption characteristics associated with pneumatic tires. One recently proposed solution to this problem is found in parent U.S. patent application Ser. No. 08/354,374, filed Jan. 12, 1994, and assigned to the assignee of the instant application. This application discloses an in-line skate wheel with an annular, radially encapsulated bladder, inside the skate wheel, the pressure of which can be adjusted by an inflation pump acting through a valve system. Therefore, the skater can adjust the wheels depending on whether increased resiliency is required or increased performance. This wheel provides the skater with the enhanced versatility associated with different wheels of different constructions without the expense of purchasing a selection of different wheels. However, this design requires greater skater "involvement" while skating since the skater is required to physically adjust the level of inflation when conditions or performance requirements change. Additionally, there is substantial expense associated with the manufacture of such wheels and the associated inflation pumps. The present invention provides the skater with similar levels of shock absorption along with increased resiliency but does not require the skater to actively adjust the wheel. At the same time, the addition of annularly spaced radial bladder rods serve to orient the bladder during manufacture and also serve to increase the level of shock absorption and resiliency beyond that of the single annular tube structure.
Many types of inflatable bladders are known in the prior art for use in a variety of applications. One field that has shown a high level of bladder development has been in athletic shoes. One such inflatable bladder is found in U.S. Pat. No. 5,406,661 which discloses a preloaded bladder and pump combination which includes a preinflated portion of the bladder system. This patent includes one bladder which is permanently inflated in combination with at least one other chamber that is inflatable at the users convenience. Although this patent discloses a multi-chamber system, the bladders are connected and are designed for use with a pump. The present invention incorporates multi-chamber bladder structure where the chambers are isolated from one another but allow the bladder structure to cooperate in carrying and distributing shock loads.
Thus, there remains a need for a pneumatic/polyurethane in-line skate wheel which is economical to manufacture and requires little or no user involvement to maintain its performance level while providing for a long and trouble free life.